Title (fr)

Publication

Application

Priority

EP 94908200 A 19930810

JP 21518892 A 19920812

JP 23969492 A 19920908

JP 25990292 A 19920929

JP 33904792 A 19921218

JP 192893 A 19930108

Abstract (en)

In a brushless motor which includes a stator (26) and a rotor (1) rotatably supported inside the stator and wherein the rotor has a yoke (2) formed by laminating a large number of steel sheets (4), the yoke has an even number of magnetic poles (5) protruding outward, and a permanent magnet (3) for a field is inserted into each, or every other, magnetic poles, the permanent magnet rotor of the present invention has a structure in which the permanent magnet for the field is inserted into a slot (6) formed in the magnetic pole, and protuberances (9) striking the side surfaces of the permanent magnet for the field are disposed at the right and left portions of the slot. Further, in the present invention, in the brushless motor of this kind, engagement pawls (12) engaging with the permanent magnet for the field are so disposed as to protrude, reliefs (13) for absorbing a bend of the engagement pawl are formed in those of the steel sheets laminated to form the yoke which correspond to the engagement pawl. The steel sheets of the yoke are deviated on one or both ends sequentially in the rotating direction. A bridge width at both ends of the slot is set to be greater than the greater one of a width capable of being punched out and a width allowed from a mechanical strength due to a centrifugal force between the width capable of being punched out, a width allowed from the number of passing magnetic fluxes and the width allowed from the mechanical strength due to the centrifugal force. Further, at least one connecting portion of gap is provided to each magnetic pole so as to laminate the steel sheets. The bridge width at both end of the slot is set to be smaller than a width from the outside portion of the permanent magnet for the field to the outside edge of the magnetic pole. <IMAGE>